Search

Wastewater issues became a complex challenge in the world. There are several methods in wastewater treatment, such as chemical, physical, biological, and the combination of each method. However, each process has advantages and disadvantages. The physicochemical methods are common methods used in wastewater treatment, such as adsorption and coagulation. Adsorption and coagulation are excellent methods to remove pollutants. The adsorption process is greatly influenced by pH, adsorbent dose, temperature, and contact time. Coagulant dose, settling time, and pH are the main factors in the coagulation process. Chemical material as an adsorbent and coagulant has been studied in previous research, but recently, to substitution chemical materials is a challenging subject. Natural substances are potential new materials in wastewater treatment and became popular due to their efficiency and environment friendly characteristics. This review investigated the role of adsorption and coagulation in wastewater treatment and the utilization of natural materials as adsorbents and coagulants.

Since adsorption is one of the best ammonium removal methods, great efforts have been made to identify new low-cost and efficient adsorbents from agricultural waste and by-products due to their abundant availability, low-cost and eco-friendly advantages, in addition to the possibility of recycling ammonium back into agricultural processes. In this study, a series of batch experiments were performed to detect new bio-adsorbents for ammonium ions removal. Among the materials tested, pomegranate peel powder showed a high affinity to adsorb ammonium ions and, furthermore, available information on ammonium adsorption by this biomaterial is still missing from the literature. First, pomegranate peel powder was characterized by the determination of different parameters such as zeta potential, iodine number, Fourier-transform infrared spectroscopy analysis, scanning electron microscopy, particle size distribution and porosity. Then, the impact of various parameters, such as pH, contact time, stirring speed, adsorbent dose and adsorbate concentration in the adsorption process, was investigated. The highest ammonium removal capacity was obtained at pH = 4 using 400 mg of pomegranate peel powder and a stirring speed of 150 rpm for an initial concentration of ammonium of 30 mg/L. The system (adsorbent, adsorbate and solution) reached equilibrium after 2 h and the data fit well with the Langmuir model with a maximum monolayer adsorption capacity of 6.18 mg/g, while kinetics were well described by the pseudo-second-order model. These results introduce pomegranate peel powder as a promising bio-adsorbent to remove and recover ammonium from aqueous solutions.

A significant representative of the third generation of raw materials is waste containing hemicellulose. Agriculture and the food industry generate a great deal of this type of waste, which has many potential opportunities for processing. Our research group investigated the pre-treatments for the enzymatic saccharification of the cellulose content of the two fractions of corn cob meal. Microwave energy communication was performed in both acidic and alkaline media. It was found that the pH of the medium influences the amount of reducing sugars, but to an almost equal extent. The yield is also significantly dependent on the starting material and the concentration of the suspension.

Microbial number reduction in spices through various treatments represents a necessity considering possible changes which may occur during spices’ storage and application in food resulting in public health risk. The present study was conducted in order to examine the effects of sterilisation and microwave irradiation treatments on total mesophilic aerobic bacteria (TMAB) and bacterial spore content reduction in black pepper. Treatments applied were: sterilisation at 130 °C during 30, 60 and 90 min; and microwave irradiation at a power level of 600 W during 1.5, 3, and 5 min. Prolongation of the sterilisation treatment expressed positive influence on TMAB and bacterial spore reduction in black pepper. Compared to the sterilisation, microwave irradiation treatment exhibited better results in terms of black pepper decontamination. Maximal decontamination regarding TMAB and bacterial spore was achieved in black pepper samples treated with microwave irradiation during 3 min. The present results suggest that microwave irradiation could be applied in black pepper decontamination considering better effectiveness compared to the sterilisation treatment.

In the present study, real car wash wastewater was purified by different coagulation/flocculation methods. As coagulant, polyaluminum chloride (‘BOPAC’), conventional iron(III) chloride, iron(III) sulfate, and aluminum(III) chloride were used, while as flocculant non-ionic and anionic polyelectrolytes were investigated. The effects of added clay mineral (Na-bentonite) and cationic surfactant (hexadecyltrimethyl ammonium bromide – ‘HTABr’) were also investigated. The use of BOPAC was significantly more effective than conventional coagulants. Extra addition of clay mineral was also beneficial in relation to both the sediment volume and sedimentation speed, while polyelectrolyte addition enhanced further the sedimentation. Moreover, the simultaneous addition of HTABr significantly enhanced the color removal efficiency due to the successful in-situ generation of organophilic bentonite. In summary, the application of 100 mg L−1 Na-bentonite with 20 mg L−1 Al3+ (from BOPAC) and 0.5 mg L−1 anionic polyelectrolyte resulted in the efficient reduction of the turbidity (4–6 NTU), the COD (158 mg L−1) and the extractable oil content (4 mg L−1) with efficiencies of 98%, 59%, and 85%, respectively. By applying organophilic bentonite in high concentration (500 mg L−1) with identical concentrations of BOPAC and anionic polyelectrolyte, significant color removal (5 times lower absorbance at λ = 400 nm) and 27% lower sediment volume were achieved.

Emulsified oily contaminants of wastewaters cannot be eliminated effectively by conventional treatments, but they pose significant risks both to the environment and to human health, therefore their...

Kutatasunk soran a mikrohullammal intenzifikalt Fenton-reakcio alkalmazhatosagat vizsgaltuk husipari szennyviz kezelese eseten. A kiserletek soran figyeltuk a Fenton-reakciohoz szukseges reagens (Fe2+ es H2O2) adagolasi dozisanak es a kozolt mikrohullamu energianak a kemiai oxigenigeny (KOI) csokkentesere (es igy a szervesanyag-tartalom csokkentesere) gyakorolt hatasat. A kutatasi eredmenyeink igazoltak, hogy a szervesanyag-eltavolitasi hatekonysag az alkalmazott Fe2+/H2O2 aranytol es az osszes kozolt MW energiatol is fugg. Magasabb dozisu Fenton-reagens nagyobb mertekű KOI-csokkenest eredmenyezett, a mikrohullamu energiakozles pedig kepes az oxidacios reakcio hatekonysagat novelni – magas kozolt MW energia eseten adott KOI-ertek csokkeneshez joval kevesebb reagens is elegendő volt. A kiserletek soran azt is igazoltuk, hogy a dielektromos vesztesegi szogtangens meresevel a szervesanyag-eltavolitas pontosan es konnyen nyomon kovethető. Abstract: Our experimental work focused on the applicability of microwave-assisted Fenton-reaction for wastewater treatment. We investigated the effects of Fenton’s reagent dosage and irradiated MW energy on the removal efficiency of chemical oxygen demand (COD). The results verified that organic matter removal efficiency is influenced by the Fe2+/H2O2 ratio and the microwave energy as well. Higher reagent dosage caused higher COD-removal, and it was proved that the microwave irradiation can enhance the efficiency of the oxidation process; the higher the MW energy was, the less reagent concentration was needed for reaching a given organic compound removal effectiveness. The experimental results also showed that measuring the dielectric loss tangent can be used to monitor the change in organic matter removal, i.e. the change in chemical oxygen demand.

Membrane-based methods of filtering are becoming increasingly popular in the food industry, but membrane fouling significantly affects filtration performance, making the characterisation of fouling mechanisms critical. This study examined the applicability of three mathematical models. The resistance-in-series model divides the total resistance into membrane resistance, reversible resistance and irreversible resistance. The Hermia models distinguish four basic blocking mechanisms, namely complete blocking, standard blocking, intermediate blocking and cake filtration. The Makardij model analyses the flux-reducing or -enhancing effects. In the experiments, different models were investigated and compared. The feed solution was two milk substitute drinks (soy and oat) that were ultrafiltered under different operating parameters (transmembrane pressures: 0.05–0.1 MPa, stirring rate: 100–400 min(−1)). By fitting the data to the models, the most characteristic blocking mechanism and the rate constant that most influenced flux could be determined.

Agricultural wastewater poses serious risks to the environment due to how it is injudiciously used and managed. We investigated the use of pomegranate peel powder (PPP) to adsorb ammonium ions from milking parlor wastewater, which is applied as a nitrogen source for cropland fertilization despite its environmental ramifications. As a valueless by-product of juice and jam industries, PPP shows promising features and characteristics as a potential bio-adsorbent for ammonium nitrogen removal and recovery. The surface characterization of PPP was performed by zeta potential measurement and attenuated total reflectance Fourier transform infrared Spectroscopy (ATR-FTIR) analysis. The adsorption studies were carried out by batch experiments where the initial ammonium nitrogen (NH4&ndash, N) concentration of studied wastewater was 80 mg/L. The effects of different operational parameters, such as pH, adsorbent dose, contact time, stirring speed, and temperature, were investigated. From kinetic studies, the equilibrium time was found to be 120 min, achieving an 81.8% removal synonym of ~2.5 mg/g NH4&ndash, N uptake. The adsorption isotherm data fitted well with Langmuir model with correlation (R2) &gt, 0.99. Meanwhile, the kinetics followed pseudo-second order model with correlation (R2) &gt, 0.99.

Our experimental work focused on the applicability of a quite novel process for wastewater treatment, i.e. a microwave (MW) irradiation-enhanced Fenton-like method. The aim of our research was to detect and evaluate the efficiency of this oxidation process, during the treatment of meat industry wastewater containing a high concentration of organic material. The efficiency was defined by the measurement of the change in COD (chemical oxygen demand, with an initial COD value of 1,568 mg L−1), and with the determination of dielectric parameters during the process. It can be summarized that MW irradiation could assist in a Fenton-like oxidation process to achieve higher organic matter removal. Furthermore, our experimental results and statistical analysis show that there can be found a correlation between the effects of applied MW energy and the dosage of H2O2/FeSO4. If the intensity of MW irradiation and the amount of FeSO4 were set higher, the decrease of COD and the increase of tanδ (the dielectric loss tangent) were definitely more significant. With the application of 60 kJ MWE and a 0.14 mgFe2+/mgCOD dosage, the COD removal efficiency was more than 40%, and the increment of tanδ was nearly threefold. Considering the effects of MW-specific process parameters, it can be concluded that the power intensity of MW–oxidation treatment has a significant effect on COD decrease, if the irradiated MW energy was set at lower (30–45 kJ) levels.

For the effective purification of emulsified oil contaminated waters advanced treatment methods have to be applied, such as membrane filtration, which is able to eliminate macro-, and even nanoscale oil droplets, however, membrane fouling is still a major problem, which prevents economic utilization. Therefore, fouling mitigation is one of the most important aspects in the field of membrane separation developments. In the present study, solely TiO2 and TiO2/carbon nanotubes (CNT) composite modified PVDF membranes were prepared and used to purify oil-in-water emulsions. Achievable fluxes, reversible and irreversible filtration resistances, fouling models, filtration efficiencies and photocatalytic activities were compared in case of different nanomaterial covered and unmodified PVDF membranes. Applying either solely TiO2 or solely CNT coating resulted in the significant reduction of total filtration resistance in both cases, but the combination of the two components (TiO2 with 1 wt% CNT) resulted in by far the highest flux and lowest resistance, meanwhile, the enhanced photocatalytic efficiency of the composite was also achieved. To the best of our knowledge, this study demonstrates the beneficial effects of the combination of TiO2 and CNT nanomaterials for the first time in the field of membrane separation of oil-in-water emulsions.

Membrane separation processes are currently proven technologies in many areas. The main limitation of these processes is the accumulation of matter at the membrane surface which leads to two phenomena: concentration polarization and membrane fouling. According to the publications of numerous authors permeate flux could be increased by sonication. Our work focuses on separation of real broth by sonicated ultrafiltration. The broth was originated from hydrolysis of grounded corn-cob by xylanase enzyme. The filtration was carried out in a laboratory batch stirred cell with a sonication rod sonicator. In our work the effect of the stirring, the intensity of sonication and the membrane-transducer distance was studied on the efficiency of the ultrafiltration and on the quality of separated enzymes. Results reveal that xylanase enzyme can be effectively separated from real fermentation broth by ultrafiltration and enzymes keep their activity after the process. Enzyme activity tests show that low energy sonication is not harmful to the enzyme.

It has been numerously verified that microwave radiation could be advantageous as a pre-treatment for enhanced disintegration of sludge. Very few data related to the dielectric parameters of wastewater of different origins are available; therefore, the objective of our work was to measure the dielectric constant of municipal and meat industrial wastewater during a continuous flow operating microwave process. Determination of the dielectric constant and its change during wastewater and sludge processing make it possible to decide on the applicability of dielectric measurements for detecting the organic matter removal efficiency of wastewater purification process or disintegration degree of sludge. With the measurement of dielectric constant as a function of temperature, total solids (TS) content and microwave specific process parameters regression models were developed. Our results verified that in the case of municipal wastewater sludge, the TS content has a significant effect on the dielectric constant and disintegration degree (DD), as does the temperature. The dielectric constant has a decreasing tendency with increasing temperature for wastewater sludge of low TS content, but an adverse effect was found for samples with high TS and organic matter contents. DD of meat processing wastewater sludge was influenced significantly by the volumetric flow rate and power level, as process parameters of continuously flow microwave pre-treatments. It can be concluded that the disintegration process of food industry sludge can be detected by dielectric constant measurements. From technical purposes the applicability of dielectric measurements was tested in the purification process of municipal wastewater, as well. Determination of dielectric behaviour was a sensitive method to detect the purification degree of municipal wastewater.

In the present study, oil in water emulsions (coil = 100 ppm; doil droplets

Water is currently becoming a strategically important material, and the importance of water and wastewater treatment technologies is therefore increasing. Wastewater from the food industry has many special features originating from its high organic matter content. Meat industry wastewater additionally has a high fat content. We investigated the effects of ultrafiltration and ozonation, individually and in combination, for the treatment of meat industrial wastewater. Ozone gas was generated from oxygen with an Ozomatic Modular 4 ozone generator (Wedeco Ltd., Germany), and filtration was carried out with a micellar-enhanced ultrafiltration (MEUF) apparatus, through a flat membrane with a surface area of 40 cm2. The experimental data revealed that pre-ozonation of the wastewater affected ultrafiltration. The flux was higher and persisted longer than in the case of non-ozonated samples. The chemical oxygen demand was decreased by ozonation treatment. The duration of ozonation and the subsequent ultrafiltration exhibited a very interesting relationship. The most important effect of ozonation was observed on membrane fouling. The fouling mechanism was modelled, and the rate constants of flux decline (k1) and deposit removal from the membrane (k2) were calculated. The effect of the Reynolds number was also shown. The aim of our work was to study the industrial effects of combined cleaning techniques, i.e. ozonation on meat processing wastewater. The optimum ozonation time was 2 to 10 min before ultrafiltration with a PES membrane with a cut-off of 5 kDa.

This study investigated the adsorption of phosphate from aqueous solutions using pomegranate peel (PP) as a bio-adsorbent. For this purpose, PP was activated via saponification using sodium hydroxide (NaOH) followed by cationization using iron chloride (FeCl3). The iron-loaded PP (IL-PP) was characterized using zeta potential measurement, scanning electron microscopy, and Fourier transform infrared analysis. The batch adsorption method was followed to determine the equilibrium time and effect of pH on the adsorption process. The full factorial design methodology was used to analyze the effects of influencing parameters and their interactions. The effective removal of phosphate up to 90% was achieved within 60 min, at pH 9 and 25 °C temperature using a 150 mg dose of IL-PP. A non-linear method was used for the modeling of isotherm and kinetics. The results showed that the kinetics is best fitted to the Elovich model (R2 = 0.97), which assumes the dominance of the chemisorption mechanism, whereas the isotherm obeys both Langmuir (R2 = 0.98) and Freundlich (R2 = 0.94) models with a maximum phosphate uptake of 49.12 mg·g−1. Investigation of thermodynamic parameters indicated the spontaneity and endothermic nature of the process. These results introduce IL-PP as an efficient bio-adsorbent of phosphate.

In the present study, TiO2-coated ultrafiltration membranes were prepared and used for oily water filtration (droplet size

In the present work, the surface and filtration properties of TiO2 coated polyacrylonitrile ultrafiltration membranes were investigated. The membranes were coated using the physical deposition method. The appropriate TiO2 coverage proved to be 0.3 mg/cm2, which formed a hydrophilic cake layer on the membrane surface. The cleanability without chemicals and the retention of the coated membranes was compared to the neat membrane after model oily wastewater filtration. The cleaning sustained of rinsing with distilled water and ultraviolet (UV) irradiation of the fouled membranes. The coated membranes have better antifouling properties; higher flux values during oily water filtration and by the mentioned cleaning process a significantly better flux recovery can be achieved. The amount of the catalyst and the irradiation time are limiting factors to the effectiveness of the cleaning process. The UV irradiation increases the wettability of the fouled membrane surface by degrading the oil layer. The coating, the continuous use, and the cleaning process do not significantly affect the membrane retention expressed in chemical oxygen demand.

Oily wastewaters are one of the major environmental pollutants in aquatic systems. This is due to the emission of a variety of industrial oily wastewaters from sources such as crude oil mining (production), refineries, petrochemical plants and transportation. The aims of this work were to investigate the treatment of oil-contaminated wastewaters with a pre-ozonation/microfiltration combined system and the effect of pre-ozonation on the microfiltration parameters. The results demonstrated that ozone pre-treatment modified the chemical nature (pH and conductivity) of oil-in-water emulsion, resulting in higher wettability of the polyethersulphone membrane. In case of salt-containing model emulsions compared to pure oil emulsions, ozone treatment was found to be more effective for membrane resistance reduction and in chemical oxygen demand retention.

Enzymes are biological catalysts that generally are designed to do one job well, but to do one job only. Therefore, the enzymes that catalyze the hydrolysis of cellulose to sugar do not break down the sugars. Enzymatic hydrolysis processes have been under development for only 10 years. The important research issues include understanding the processes necessary to render the crystalline cellulose easily digestible, understanding and improving the basic mechanisms in the hydrolysis step, and developing better and less expensive enzymes. The other way to make a process less expensive may be the recycling of enzymes. The essential unit operation in the bioethanol production is the cellulose enzymatic degradation, so the question of recycling is very important. In our work the sonication assisted ultrafiltration was investigated as a potential method for enzyme recycling. The results showed the ultrasound effects the permeate flux since the resistance is reduced by the sonication. The sonicated enzyme keeps its activity so the recycling mechanism might be used for bioethanol production.

Nowadays, the membrane filtration technique is a commonly used method for the separation of whey. The most significant limitation of membrane applications is fouling, which causes flux decline. During this work, regenerated cellulose membranes covered by TiO2-nanoparticles were investigated and applied to the separation of whey solution. Experiments were carried out in a dead-end ultrafiltration cell, and the changes in filtration parameters and the photocatalytic effects of the UV irradiated TiO2 modified membrane surface on the membrane fouling were examined. Our results showed that the water flux decreased with increasing TiO2 layer thickness, but the retention of turbidity and of COD increased. After separation, the membrane surface was cleaned by UV irradiation by means of photocatalytic oxidation. It was found that the original flux was recoverable, while the retention of the membrane decreased after cleaning.

The largest quantities of by-products of dairy processing originates from the cheese making. Whey proteins are used for animal feeding and human nutrition as well, for example in dry soups, infant formulas, and supplements. The fat components of the whey might impair its use. The aim of our experiments was to investigate the separation of the lipid fraction of whey. The microfiltration is said to be a gentle and energy efficient method for this task. During the measurements 0.2 μm microfiltration membranes were used and the membrane separation was enhanced by vibration, inserting static mixer and air sparging. The de-fatting efficiency, the retention of the whey components, the flux values, and the resistances in different combinations were compared in this paper.

The importance of biofuels is growing for both environmental and economic point of view. The usage of wastes in bio-ethanol production is investigated in our paper. Cellulose contained wastes i.e. byproduct of tobacco is used for experiments. The paper is focused mainly on the investigation of the enzyme recovery that followed the saccharification process. The membrane filtration combined with sonication was used for enzyme recovery. Our results show that recovered enzyme did not lose its activity. The patterns were originated from fermented solutions made from tobacco byproducts. Based on our results, the ultrasound accompanied by a membrane separation would be a possible and effective operation of bio-ethanol production technology.

Membrane fouling is still a critical issue which limits the application of industrial membrane utilizations. Membrane processes operating at a high shear rate are frequently used to control flux decline by reducing the deposition of particles on the membrane surface. In this work, ultrafiltration (UF) of a dairy model and industrial wastewaters was investigated. Membrane module vibration and no-vibration mode were compared by a laboratory mode vibratory shear enhanced processing device during membrane filtration with the same operational parameters. Membrane fluxes, rejections, and energy consumption were measured and calculated for comparison of the vibration effectiveness. Turbidity, chemical oxygen demand, and total organic carbon were measured. The UF experiments were carried out with constant parameters at a temperature of 50°C and recirculation flow rate of 910 L h−1 at 0.8 MPa. Furthermore, to understand the fouling mechanisms in depth, contact angles of the clean, prewetted, and fouled mem...

In process industries, a large amount of wastewater is generated in the form of oil-in-water emulsions, which cannot be treated effectively using traditional physical methods. The aim of our investigation was to examine the applicability of the membrane technique and the effect of pre-ozonation in oily wastewater treatment. Pre-ozonation followed by microfiltration (MF) was investigated to determine the main effects of ozonation on the oily water and the filtration parameters such as permeate flux, organic content retention and membrane fouling. Experiments were carried out with a laboratory-scale batch-stirred filtration device, using polyethersulphone MF membranes with a pore size 0.2 μm. The model oily wastewater that was used in these experiments contained petroleum. The results demonstrated that the chemical oxygen demand could be eliminated more effectively through the combination of ozone pre-treatment and membrane filtration, compared to membrane filtration alone.

The ultrafiltration (UF) of model oily wastewater containing an emulsifier was investigated in order to determine the main parameters affecting the flux, retention and membrane fouling. The experiments were carried out with a laboratory UF device, using regenerated cellulose UF membranes. The finding that the fall in flux with time correlated best with the cake formation model is in accordance with the result that increasing resistance during filtration is caused predominantly by the concentration polarization, while the participation of membrane fouling in the total resistance is negligible. Analysis of the parameters affecting the UF of oily wastewater demonstrated that the flux is mainly influenced by temperature and concentration (besides the membrane pore size), while the concentration and the stirring speed are the parameters affecting the resistance. The retention increased slightly with concentration, but this was mainly determined by the membrane pore size.

The development of second-generation biofuels from cellulosic/lignocellulosic biomass has advantages from energy and environmental aspects, but the overall cost of the process is mainly dependent on the cost of the enzymes. Enzyme recovery and recycling is one of the most important and effective means of increasing the efficiency of enzymatic hydrolysis processes by lowering the enzyme costs. The primary objective of this study was to investigate the possibilities of enzyme recovery by membrane separation. Ultrafiltration (UF) membranes with various cut-off values and materials were used to recycle cellulase and cellobiase in model solutions and cellulosic hydrolysates. The membrane separation process was followed by determination of the flux, and its efficiency of it was measured via sugar and protein retention, and the resistances were also calculated. A polyether–sulfone membrane with a cut-off value of 5 kDa, (PES5) operated at 26.8 L m−2 h−1 with 87.3% protein rejection while a thin-film mem...

This paper reports on the process optimization study of anthocyanin extraction from black currant marc by microwave-assisted extraction (MAE) using acidic solvents. Maximum yields of anthocyanins were achieved at pH 2 with an extraction time of 10 min with a microwave power of 700 W. The anthocyanin yields in MAE were compared with those obtained by conventional solvent extraction (CE) using citric or hydrochloric acids, and citric acid and water with a sulfur concentration of 50 ppm. A significant reduction of extraction time was achieved using MAE; maximum anthocyanin yield was obtained after 10 min using MAE, while using CE only after 300 min. Furthermore, the amount of solvent used halved; the mass ratio of marc to solvent was 1:40 in CE and 1:20 in MAE. Additionally, the final anthocyanin concentration in the solvent phase of MAE increased by 20 % compared to the conventional extraction with hydrochloric acid at pH 2 and temperature of 80 °C. The results suggest that microwave-assisted extraction is a more efficient technique for the extraction of valuable compounds from black currant residue.

This study investigated the performance of a Vibratory Shear Enhanced Processing (VSEP) using ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membrane system for decreasing of chemical oxygen demand (COD) from dairy wastewater. Three commercially available membranes having different pore sizes were used to compare their relative efficiency for COD decreasing. Permeate flux and membrane rejection of COD were measured as well as mean shear rates and the specific energy demands of vibrated and non-vibrated methods were calculated and compared. Furthermore, flux and COD rejection were also studied increasing by transmembrane pressure (TMP) and vibration amplitude. Concentration test were performed by UF, NF and RO.

Microwave (MW) irradiation is a relatively new possibility of conditioning and pretreating for wastewater sludge. Following its application in the telecommunications and food-industries, the environmental use of this technique has come into the limelight in recent years, and has become increasingly popular. Various publications have dealt with the examination of the effects of MW irradiation in municipal sludge-handling processes. We focused on the effects of MW irradiation at different power levels on solubilization (sCOD/tCOD), biodegradation and anaerobic digestion of sludge from the food-industry. For evaluating the efficiency of MW pre-treatment, the changes in the soluble fraction of the organic matter, the VS/TS ratio, the biogas yield, the methane content in the biogas, and the rate of batch mesophilic digestion were used as control parameters. Additionally, the energetic efficiency of MW pre-treatment was also examined. The results were compared with those of conventional heat (CH) treatments of the same sludge. The MW treatment proved to increase both the sCOD/tCOD and the VS/TS ratio. Furthermore, the biogas and methane yields increased during the digestion of the MW-pretreated food-industry sludge. A higher MW power level generally enhanced the biogas and methane production. Energetically, the most economic pre-treatment of sludge from dairy and meat processing was at a power level of 1.5 Wg(-1) and 2.5 Wg(-1) MW respectively; the surplus energy content of the enhanced biogas product could not compensate the extra energy demand of the stronger MW pre-treatments.

Extraction of pectic substances from solid agro-wastes and the application of recovered pectin in the food, pharmaceutical and cosmetic industry can significantly contribute to a more economic and environmentally sound agro-industrial production. Thus investigation of the physicochemical properties of extracted pectic substances seems important not only from human health preservation considerations, but their advantageous properties can be confirmed for the possible manufacturers, potential processing, as well. Therefore, in this work pectic substances were extracted from red currant, black currant, raspberry, blackberry and elderberry press residues by hot water and the composition, antioxidant activity, total phenol, anthocyanin content and the color coordinates of pectins were determined. The results show that the pectin colors fall in the range between reddish purple (black currant and elderberry) and yellow (citrus and apple). Moreover some of the pectins in a powder form have different color coordinates than in the form of aqueous solutions or gels. This might be very important when the pectins are selected for different production processes. The anthocyanin content of pectin preparations is lower than the values of fruit juices. It can be concluded that the colorants found in pectin preparations belong to the group of phenolics and have adequate antioxidant capacity, which is extremely beneficial for human health. As a summary it was concluded that the investigated pectins can be easily extracted and successfully used as natural colorants or antioxidants since they have adequate antioxidant activity, total phenol and anthocyanin content and suitable color coordinates.

Microwave irradiation is a novel and very promising technology for sludge conditioning. As pretreatment, it has a verified beneficial effect on the microbial degradation and anaerobic digestion of sewage sludge, but in present work we dealt with the applicability of microwave pretreatments for food industrial sludge. However, studies cannot be found that specialize on the effects of the MW treatments with different intensities on the anaerobic digestion of sludge. In our work we focused on the examination of the effect of MW pretreatment for 0.5, 2.5, and 5 W/g on the carbonaceous biochemical oxygen demand (CBOD5), solubilization of organic matters (sCOD/tCOD), and the mesophilic anaerobic digestion of dairy sewage sludge. It can be concluded that the MW pretreatments were appropriate to enhance the efficiency of anaerobic digestion. With MW pretreatments the specific biogas product could be increased from 220 mL g−1 to more than 600 mL g−1 because of the increased solubility (from 9.7% to more than 40%), and the enhanced accessibility of organic compounds for decomposing bacteria. © 2010 American Institute of Chemical Engineers Environ Prog, 2011

This paper evaluates the efficiency of ultrafiltration and the effects of processing on the total anthocyanin and flavonol contents of black currant juice at chosen operational conditions. Ultrafiltration of black currant juices was carried out using Biomax 100 kDa polyethersulfone membrane. Ultrafiltration was used to process the juice prior concentration by reverse osmosis; with the aim to enhance the efficiency of the concentration process in terms of permeate flux. To avoid the fouling of the membrane, the juices were depectinized with Panzym Super E liquid enzyme preparation. The ultrafiltration was carried out at a transmembrane pressure of 2 bars and the operating temperature of 25 °C. The effect of processing on the valuable anthocyanin and flavonol content of the juices was evaluated based on the results of high-performance liquid chromatography analyses. The article includes detailed analyses of anthocyanin and flavonol compounds of the enzyme treated and ultrafiltered juice as compared with the original juice. The results indicate that, due to the enzymatic treatment, the valuable compound content of the juice increases. However, the ultrafiltration process resulted in a significant loss of a valuable content; 54% of total flavonol and 50% of total anthocyanins maintained in ultrafiltered juice when compared to the feed samples.

Whey is used a nutritious protein source. The process of whey concentration was important historically, as the application of ultrafiltration (UF) in the dairy industry started with the separation and concentration of whey proteins from whey. In order to improve the performance of UF, it is beneficial to limit the extent of fouling of the membranes. In this study, the performances of a vibratory shear-enhanced filtration process and a batchstirred dead-end ultrafiltration process for the concentration of cheese whey were investigated with UF, C-30F regenerated cellulose and polysulfone 30 kDa nominal molecular weight limit membranes. The separations of protein and dry matter were examined by means of an IR technique and the Kjeldahl method. The turbidity and the chemical oxygen demand were also measured during concentration experiments. The volume of the pretreated (pasteurized) feed whey was decreased to 50% and 17.6% in the stirred and vibrated membrane processes, respectively.

The membrane technique of microfiltration (MF) was used to investigate the degree of reduction of the membrane resistance. The application of dolly-particles seems very beneficial for some MF processes with conventional equipment. A pile of bakelite enhanced the local shear near the membrane surface. This phenomenon depends greatly on the components and properties of the feed suspension; the shear force is dependent on the radius and the amount of the particles. This approach has been successful in increasing fluxes of MF. The larger particles induce a much higher shear-induced diffusion and therefore dramatically improve mass transfer. Increasing size of the bakelite particles could be associated with increasing flux. To prevent the fouling of MF membranes during the processing of chalk-dust solutions, a high degree of turbulence should be introduced in the membrane surface. The application of microparticles (bakelite) as dolly-particles was investigated for this purpose. The experiments were carried out...

In this study the performance of a vibratory shear-enhanced processing system (VSEP) for the concentration of cheese whey was assessed and compared with a classical, cross-flow, plate and frame membrane configuration system (3DTA) with the same membrane (i.e. a C30F UF regenerated cellulose UF membrane with a 30 kDa molecular weight cutoff). The temperature and pressure dependences of the permeate flux, the permeate flux reduction ratio, the resistances and the rejection values were investigated. Comparison of the two systems revealed a definite advantage for the VSEP system equipped with the same membrane and operated at the same pressure and temperature. The VSEP system yielded a permeate protein retention of 99.7% vs. 74.5% for the 3DTA system, together with a higher average flux: 54 L m −2 h −1 vs. 44.2 L m −2 h −1 . The flux reduction ratio ( J/J0 ) was 0.60 vs. 0.42, and the total resistances 2.87*10 +13 m −1 vs. 4.54*10 +13 m −1 for the VSEP and 3DTA system, respectively.

Whey, a side-product of the cheese-making and casein industry, is a nutritious protein source. The nutritional, biological and functional properties of whey proteins make them attractive and explain why an active whey industry has been developing over the last 30 years. The preconcentration of whey at its production site is the major field of application of membrane separation. The high salt content of whey (8–20% dry matter) gives rise to numerous processing difficulties, a low lactose crystallization rate, and fouling in microfiltration (MF) and ultrafiltration (UF) performed to produce whey protein concentrates. In order to improve UF performance, it is advisable to limit fouling of the membranes by selecting an appropriate flux or shear stress ratio [1]. In this study, the performance of a vibratory shear-enhanced processing system (VSEP) for the concentration of cheese whey was assessed and compared with a classical, cross-flow, plate and frame membrane configuration system (3DTA) with the same membr...

The aim of this study was to examine the applicability of reverse osmosis (RO) for the concentration of blackcurrant juice by AFC-80 polyamide tubular membrane that has a salt rejection greater than 80%. The fresh juice had a total soluble solids content of about 16.5°Brix. The effect of centrifugation followed by depectinization with two commercially available pectinase enzyme preparations (Panzym Super E and Trenolin Rot DF) on the permeate flux has been evaluated. For the description of the concentration process, the resistance-in-series model has been used. It was concluded that the applied RO membrane is suitable for concentration of blackcurrant juice up to 28.6°Brix, which was achieved with the juice that had been treated with Panzym Super E. The total resistances were calculated and compared, taking into account membrane fouling and polarization layer resistance.

In this paper, nanofiltration (NF) combined with continuous variable volume diafiltration (CVVD) of cottage cheese whey (also known as acid whey) was investigated to simultaneously concentrate and partially demineralize it. The experiments were carried out in a laboratory NF equipment using a flat sheet membrane with the effective area of 0.046 m2 and 96% sucrose rejection. Fat, protein, lactose and total solid content of the samples were analyzed by Infrared Milk Analyzer Bently 150. Ion composition of the samples was determined by ICP-MS instrument. The concentrations were carried out at different values of the ratio of the volume of dialyzation water and the volume of permeate (α). The degree of demineralization of monovalent ions reached 70% and 90% at 2.5 volume concentration ratio, and at diafiltration and permeate volume ratios of 0.5 and 0.75, respectively. The amount of multivalent ions increased continuously during the NF combined with CVVD of acid whey. The rejection of the valuable compounds of whey such as protein and lactose was over 90%.

The main goal of our work was to examine the possibility of using membrane separation to concentrate sweet whey, which could then be used as the basis of more products (e.g., ice cream, soft drinks containing whey).Whey from cheese making was concentrated by nanofiltration. The operating parameters were determined in permeate recirculation mode, and the concentration experiment was carried out under optimal conditions. The analytical assay of the permeate and concentrate such as total soluble solid content (TSS), protein content, and lactose content was determined using infrared measurements. The retention of lactose was over 95% up to 3.0 volume concentration ratio (VCR) at 20-bar transmembrane pressure. The analysis of the process was based on the resistance in series model and the van’t Hoff law. The model parameters were determined on the basis of lactose content, assuming that lactose is the key component of whey. The values of these parameters are the concentration polarization (β = 1.68) and total resistance (R TOT = 1.60 × 1014 m−1). The procedure was also repeated based on TSS, and the value of the total resistance was almost the same (R TOT = 1.59 × 1014 m−1). Due to this, the applied models describe appropriately the batch membrane concentration process of whey. The lactose concentration can be used for the calculation instead of TSS, which simplifies the job of estimating the model parameters.